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EP0281035B1 - Procédé de surveillance pour la détermination électrodynamique de l'épaisseur et des erreurs - Google Patents

Procédé de surveillance pour la détermination électrodynamique de l'épaisseur et des erreurs Download PDF

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Publication number
EP0281035B1
EP0281035B1 EP88102926A EP88102926A EP0281035B1 EP 0281035 B1 EP0281035 B1 EP 0281035B1 EP 88102926 A EP88102926 A EP 88102926A EP 88102926 A EP88102926 A EP 88102926A EP 0281035 B1 EP0281035 B1 EP 0281035B1
Authority
EP
European Patent Office
Prior art keywords
delay line
signals
signal
electrodynamic
evaluation unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88102926A
Other languages
German (de)
English (en)
Other versions
EP0281035A2 (fr
EP0281035A3 (en
Inventor
Jörg Dipl.-Ing. Quittkat
Gerhard Dipl.-Ing. Thiel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP0281035A2 publication Critical patent/EP0281035A2/fr
Publication of EP0281035A3 publication Critical patent/EP0281035A3/de
Application granted granted Critical
Publication of EP0281035B1 publication Critical patent/EP0281035B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
    • G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
    • G01B7/063—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using piezoelectric resonators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B17/00—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • G01B21/08—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness for measuring thickness

Definitions

  • the invention relates to a method for monitoring electrical components of a device for electrodynamic wall thickness and error testing, in which a transmitter generates short-term signals that are fed via a transmitter coil of an electrodynamic converter into the workpiece to be tested, where the signals are reflected and where reflected signals of a receiver coil and from there via an amplifier to an evaluation unit.
  • the electrical transmission signal generated by the transmitter is fed into the workpiece to be tested via the electrodynamic converter.
  • This transmission signal has a very high energy.
  • the signal is reflected in the workpiece and, after being converted into an electrical signal, is fed by the converter to the evaluation unit for evaluation.
  • the reflected electrical signal has a very low energy compared to the transmitted signal, so that a sensitive amplifier is necessary.
  • the evaluation unit records the time between the occurrence of the transmission signal and the reception of the reflected signal as well as the amplitude of the reflected signal.
  • the aforementioned time period and also the amplitude of the reflected signal are determined not only by the workpiece to be tested, but also by the parameters of electrical components and supply lines. Occur at these parameters Changes, then this leads to changes in the time period between the occurrence of the transmission signal and the reception of the reflected signal and in the amplitude of the reflected signal. This in turn leads to incorrect measurements, since these changes are usually not recognized.
  • a method for determining the wall thickness of workpieces is known from DE-A-3 327 526, in which a transversely drilled groove is arranged in a lead body as a test reflector. The signal reflected by this test reflector is monitored. With different test head types, the test reflector is located at a different location. The test reflector is therefore mainly used to identify which type of test head is currently in use. If the temperature at the test head is increased, the signal transit time in the lead body changes. The test signal reflected at the test reflector can therefore give an indication of an excessively high temperature of the test head.
  • the task is to design a monitoring method of the type mentioned at the outset in such a way that changes in the parameters of components which influence the time period between the occurrence of the transmission signal and the reception of the reflected signal and its amplitude can be reliably detected.
  • the object is achieved according to the invention in that the signals generated by the transmitter for delay are fed to a delay line which contains at least one attenuator and which is connected to the evaluation unit via the electrodynamic converter, and in that delayed signals in the evaluation unit have a setpoint of delayed signal can be compared.
  • the provision of the delay line specifies a defined period of time between the occurrence of the transmission signal and the reception of the delayed signal.
  • This time period (predetermined target time) is not influenced by the workpiece to be tested; however, this period of time is influenced when time-influencing parameters of components of the monitoring system change. A deviation of the actual time measured here from the predetermined target time is detected in the evaluation unit and recognized as an error.
  • the attenuator ensures that the energy of the delayed signal is in the range of the energy of the reflected signals that the evaluation unit normally evaluates. If, for example, the energy of the transmission signal deviates from the target energy as a result of an error in the transmitter, then the delayed signal has a correspondingly lower energy, which the evaluation unit recognizes as an error by comparison with the target energy of the delayed signal. The energy of the delayed signal is also not affected by the workpiece to be tested.
  • the delay line can be an ultrasound delay line or an electromagnetic delay line.
  • an ultrasound delay line has at least one piezoelectric or magnetostrictive transducer and a sound conductor connected to it.
  • the signals are reflected back to the converter in the sound conductor, for example.
  • the natural frequencies of the piezoelectric or magnetostrictive transducer and the electrodynamic transducer are approximately the same, for example.
  • the attenuator is, for example, at least one resistor connected in front of the delay line.
  • the evaluation unit is assigned, for example, at least one time gate circuit which opens on the one hand when the reflected signal occurs and on the other hand when the delayed signal occurs.
  • a transmitter 1 is provided in a known manner, the transmission signal of which is fed to an electrodynamic converter 2.
  • this electrodynamic converter 2 consists of a transmitter coil 3 and a receiver coil 4, which are arranged on a workpiece 20 to be tested.
  • the coils 3, 4 are each connected to ground with one end.
  • An evaluation unit 6 is connected to the receiving coil 4 via an amplifier 5 and two time gates 19 A and 19 B.
  • the time gate circuits 19 A and 19 B can be controlled from the transmitter 1 via lines 33, 34.
  • the transmitter 1 generates a transmission signal 7, which consists of a short AC signal.
  • the reception coil 4 converts the reflected signal into an electrical signal 8, which is fed to the evaluation unit 6 via the amplifier 5.
  • the structure and mode of operation of the circuit are known.
  • an attenuator consisting of two ohmic resistors 9, 10. These resistors 9, 10 are connected in series between the output of the transmitter 1 and ground.
  • a piezo oscillator 11 is connected to the connection point P between the two resistors 9, 10. This piezo oscillator 11 is arranged on one end of a sound conductor, specifically a plexiglass rod 12. The piezo oscillator 11 and the plexiglass rod 12 together form an ultrasound delay line.
  • the transmission signal 7 generated by the transmitter 1 is thus not only supplied to the transmission coil 3, but also to the piezoelectric oscillator 11 via the first resistor 9, which converts it into an ultrasound signal that propagates in the plexiglass rod 12 and returns at the other end 13 of the rod 12 is reflected on the piezo oscillator 11.
  • the back and forth ultrasonic signals are identified by two arrows.
  • the reflected ultrasound signal is in turn converted into an electrical signal which is supplied to the transmitter coil 3 in a damped manner by the resistors 9, 10. From there it is coupled or transformed to the receiving coil 4 and fed to the evaluation unit 6 via the amplifier 5 as a delayed and damped signal 14.
  • the evaluation unit 6 is preceded by two time gate circuits 19 A, 19 B which temporarily block its input.
  • the first time gate circuit 19 A opens within the time range in which the reflected signals 8 occur. This is illustrated by curve 15.
  • the second time gate circuit 19 B opens in the time range in which the delayed and damped signal 14 occurs. This is illustrated by curve 16. In this way, further reflection signals following the reflection signal 8 are masked out.
  • the evaluation unit 6 preferably contains a setpoint comparator 28 for the actual / setpoint comparison and a display device 32 for the difference between the setpoint and actual value, ie of (A * -A) and / or (T * -T) .
  • An alarm device 35 can also be present.
  • the natural frequency of the piezo oscillator 11 is preferably in the natural frequency range of the electrodynamic converter 2.
  • an electromagnetic delay line can also be provided, which consists of T or ⁇ elements known as such.
  • the delayed and attenuated signal is generated here by reflection of the transmission pulse at the open or short-circuited end of the electromagnetic delay line. If this electromagnetic delay line is made up of longitudinal inductors and transverse capacitors, then the signal is damped by the ohmic resistors of the longitudinal inductors, so that the damping resistors 9, 10 can be omitted.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Length Measuring Devices Characterised By Use Of Acoustic Means (AREA)

Claims (8)

  1. Procédé pour contrôler des composants électriques d'un dispositif de contrôle électrodynamique des épaisseurs de paroi et des défauts, et selon lequel un émetteur (1) produit des signaux de brève durée (7), qui sont envoyés, par l'intermédiaire d'une bobine d'émission (3) d'un transducteur électrodynamique (2), dans la pièce à contrôler (20), dans laquelle les signaux (7) sont réfléchis, et selon lequel les signaux réfléchis (8) sont envoyés à une bobine de réception (4) et, à partir de là, et par l'intermédiaire d'un amplificateur (5), à une unité d'évaluation (6),
    caractérisé par le fait que les signaux (7) produits dans l'émetteur (1) sont envoyés, afin d'être retardés, à une ligne à retard (11,12), qui comporte au moins un circuit d'affaiblissement (9) et qui est raccordée, par l'intermédiaire du transducteur électrodynamique (2), à l'unité d'évaluation (6), et que des signaux retardés (14) sont comparés dans l'unité d'évaluation (6) à une valeur de consigne pour un signal retardé (14).
  2. Procédé de contrôle suivant la revendication 1, caractérisé par le fait que la ligne à retard est une ligne à retard à ultrasons (11,12).
  3. Procédé de contrôle suivant la revendication 1, caractérisé par le fait que la ligne à retard est une ligne à retard électromagnétique.
  4. Procédé de contrôle suivant la revendication 2, caractérisé par le fait que la ligne à retard à ultrasons (11,12) comporte au moins un transducteur piézoélectrique ou magnétostrictif (11) et un conducteur de guidage du son (12), qui y est raccordé.
  5. Procédé de contrôle suivant la revendication 4, caractérisé par le fait que les signaux sont envoyés par réflexion au transducteur (11), dans le dispositif de guidage du son (12).
  6. Procédé de contrôle suivant la revendication 4 ou 5, caractérisé par le fait que les fréquences propres du transducteur piézoélectrique ou magnétostrictif (11) et du transducteur électrodynamique (2) sont approximativement identiques.
  7. Procédé de contrôle suivant l'une des revendications 1 à 6, caractérisé par le fait que le circuit d'affaiblissement est au moins une résistance branchée en amont de la ligne à retard (11,12).
  8. Procédé de contrôle suivant l'une des revendications 1 à 7, caractérisé par le fait qu'à l'unité d'évaluation (6) est associé au moins un circuit formant porte de commande temporelle (19 A, 19 B), qui s'ouvre, d'une part, lors de l'apparition du signal réfléchi (8), et, d'autre part, lors de l'apparition du signal retardé (14).
EP88102926A 1987-03-05 1988-02-26 Procédé de surveillance pour la détermination électrodynamique de l'épaisseur et des erreurs Expired - Lifetime EP0281035B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873707048 DE3707048A1 (de) 1987-03-05 1987-03-05 Ueberwachungssystem bei der elektrodynamischen wanddicken- und fehlerpruefung
DE3707048 1987-03-05

Publications (3)

Publication Number Publication Date
EP0281035A2 EP0281035A2 (fr) 1988-09-07
EP0281035A3 EP0281035A3 (en) 1990-05-30
EP0281035B1 true EP0281035B1 (fr) 1993-02-10

Family

ID=6322324

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88102926A Expired - Lifetime EP0281035B1 (fr) 1987-03-05 1988-02-26 Procédé de surveillance pour la détermination électrodynamique de l'épaisseur et des erreurs

Country Status (3)

Country Link
US (1) US4882539A (fr)
EP (1) EP0281035B1 (fr)
DE (2) DE3707048A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH689190A5 (fr) * 1993-10-19 1998-11-30 Hans Ulrich Meyer Instrument de mesure de longueurs ou d'angles.
CN100334421C (zh) * 2005-01-21 2007-08-29 天津大学 工件壁厚与尺寸形位误差自动测量系统
CN108007402A (zh) * 2017-12-07 2018-05-08 青岛河澄知识产权有限公司 一种油膜厚度静态标定方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3340466A (en) * 1962-04-12 1967-09-05 Hitachi Ltd Nondestructive testers utilizing highfrequency and low-frequency eddy currents to test for surface and subsurface defects
DE1573611A1 (de) * 1965-09-11 1970-04-16 J Und H Krautkraemer Ges F Ele Schwingeranordnung fuer die Werkstoffpruefung und Wanddickenmessung nach dem Ultraschallechoverfahren
DE2853170A1 (de) * 1978-12-08 1980-06-19 Deutsch Pruef Messgeraete Verfahren und vorrichtung zur dickenmessung an prueflingen mittels ultraschalles
US4342971A (en) * 1980-12-30 1982-08-03 E-Systems, Inc. Continuously variable surface acoustic wave delay line
US4437332A (en) * 1982-09-30 1984-03-20 Krautkramer-Branson, Inc. Ultrasonic thickness measuring instrument
DE3401144C1 (de) * 1984-01-14 1984-10-25 Krautkrämer GmbH, 5000 Köln Schaltungsvorrichtung zur Korrektur des Schallaufwegfehlers bei der Wanddickenmessung mit Ultraschallimpulsen

Also Published As

Publication number Publication date
EP0281035A2 (fr) 1988-09-07
EP0281035A3 (en) 1990-05-30
DE3878267D1 (de) 1993-03-25
DE3707048A1 (de) 1988-09-15
US4882539A (en) 1989-11-21

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